JP2003094484A - Two-color molding method and mold device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the gate cut of a resin bridge formed in a connection channel for packing a resin in a surrounding part provided in a display in a main body surface by rotation. SOLUTION: An inside body 41 in which the display 42 for characters, numerals, etc., in a form having the surrounding part 43 is partially formed on the upper surface, and a pair of gate holes 44 is bored in the inner and outer parts of a display 42a forming the surrounding part 43 is primarily molded by injecting a resin. The connection channels 5 of both gate holes 44 are formed in the lower surface of the inside body 41. Resins of different colors are injected in the same face with the display 42 on the upper surface of the inside body 41, and a main body 45 is secondarily molded into the surrounding part. The gate cut of the resin bridges 51 of the connection channels 5 formed with the main body 45 is done by the rotation of the resin bridges 51 before a molding 4 is demolded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a two-color molded product such as a key top or a license plate having a display of characters, numbers, etc. on the surface of a main body and a mold device.

[0002]

In the two-color molding method, an inner body having a display portion for letters, numbers, etc. partially projected and molded on the upper surface is primary-molded by injection of resin, and the main body is mounted on the upper surface of the inner body. The resin to be formed is secondarily formed by injection to expose the upper surface of the display unit on the surface of the main body, whereby a two-color molded product having a display of letters, numbers, etc. on the main body surface, such as a key top or license plate, The display plate etc. are molded.

In this two-color molding method, in order to clarify the form of the in-plane display, the inner body integrated with the display body and the main body covering the upper surface are molded with a resin of a different color, but the inner body side is transparent. It is also possible to form a product in which an in-plane display is illuminated by an internal light source by molding with a resin and a main body side with a light-shielding opaque resin.

Even if the display body is entirely surrounded by English letters such as A, B, O, P and numbers such as 4, 6, 8, 9, etc., the display body forming the surrounding portion is Molding can be performed by forming a pair of gate holes in the inner and outer positions and providing the connecting grooves for both gate holes on the lower surface of the inner body, but after molding the resin bridge on the back side of the molded product generated in the connecting grooves. It is necessary to cut the gate. Conventionally, the resin bridge is fixed in the movable core mold by undercut, and the gate cut is performed by using the protruding force of the molded product at the time of mold release. There is a problem that the gate cannot be cut out after it comes out, and if it is deep, it becomes difficult to project the resin bridge from the core mold.

An object of the present invention is to ensure the gate cutting by performing the gate cutting of the resin bridge on the back surface of the molded product by rotating itself, and at the same time, the structure of the portion forming the resin bridge of the mold. It is to provide a new two-color molding method and a mold device that can simplify the manufacturing process.

[0006]

According to the two-color molding method of the present invention for the above object, a display body such as letters and numbers having a surrounding portion is partially provided on the upper surface to form the surrounding portion. The inner body, which has a pair of gate holes at the inner and outer positions of the display body, is primarily molded by injection of resin, and the connection grooves for both gate holes are formed on the lower surface of the inner body. The main body is secondarily molded into the surrounding part by injecting the same as the display body, and the gate cut of the resin bridge on the back surface of the molded product that occurs together with the main body is performed by rotating the resin bridge before releasing the molded product. , Is.

Further, in the two-color molding method of the present invention, a display body such as letters and numbers having a surrounding portion is partially projected on the upper surface, and a pair of inner and outer positions of the display body forming the surrounding portion are provided. The inner body with the gate holes is primary molded by injection of transparent resin that can display illumination, and the connection groove for both gate holes is formed on the lower surface of the inner body, and then the opaque resin is displayed on the upper surface of the inner body. It is said that the main body is secondarily molded by injecting flush with the body to the inside of the surrounding part, and the gate cut of the resin bridge on the back surface of the molded product generated with the main body is performed by rotating the resin bridge before releasing the molded product. It is a thing.

In the mold apparatus of the present invention, a mold surface for molding a display body such as letters and numbers having a surrounding portion, and gate holes for the inside and outside of the molding surface of the display body forming the surrounding portion. A first fixed mold having a cavity for molding an inner body having a pair of protrusions, and a second fixed mold having a cavity for molding the main body on the upper surface of the inner body excluding the display body, with the inner body serving as a mold surface of the cavity. A movable die including a fixed die and a core die that closes the lower surface of the inner body by closing the first fixed die and the second fixed die together with the inner body to form a main body on the upper surface of the inner body. And a rotating rod and a rotating means that are rotatably provided inside the movable mold and have their front end surfaces flush with the core mold surface, and a plate-like front end portion that is fitted into the center of the rotary rod. Connection groove forming pin facing the pair of protrusions so that they can be separated from each other, and the connection groove forming pin Comprising a projecting plate which is connected a rear end projecting from the down of the rotating rod, is that.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the drawings, 1 is a first fixed mold for primary molding, 2 is a movable mold, and 3 is a second fixed mold for secondary molding. The fixed molds 1 and 3 are alternately closed by means of means or slide moving means.

The first fixed mold 1 has a cavity 11 for molding the inner body of the key top.
Is a mold surface 12 for molding a display body (for example, the English letter A) such as letters and numbers having a surrounding portion, and a pair of gate holes for inside and outside of the mold surface 12a of the display body forming the surrounding portion. It has projections 13, 13.

While the movable die 2 is closed with the first fixed die 1 to form the lower surface of the inner body, as shown in FIG.
A second fixed mold 3 having a cavity 31 for molding the main body on the upper surface of the inner body is closed, and a core mold 21 for molding the main body on the upper surface of the inner body is provided. A rotary rod 22 having a tip end surface flush with the core die surface is rotatably provided inside the movable die 2, and a tip end portion 23a of a shaft portion is provided at a central portion of the rotary rod 22. Connection groove forming pin 23 formed in a circular shape
However, the distal end portion 23a is fitted and inserted so as to freely come into contact with and separate from the pair of protrusions 13, 13.

The rotary rod 22 of this connection groove forming pin 23
The rear end of the shaft portion projecting from is formed on a flange 23b, and the flange 23b is sandwiched by a projecting plate 25 provided to be movable back and forth in a space 24 in the rear part of the movable mold 2, and a connecting groove is formed together with the projecting plate 25. The pin 23 is connected so as to move backward in the rotating rod. The rear end of the rotary rod 22 is housed in a gear box 27 fixed in the front part of the space 24 together with a gear 26 provided around the rotary rod 22, and the gear 26 is meshed with a rack 28 and a supporting gear 29 therein. Then, the rotation rod 22 is rotated by 90 ° together with the connection groove forming pin 23 by the rack 28.

In order to injection-mold a two-color molded product 4 such as a key top shown in FIG. 8 using the above mold apparatus, first, as shown in FIG. 4, the first fixed mold 1 and the rotary rod 22 are connected. The cavity 11 of the inner body 41 is formed by closing the movable die 2 in which the tip end surface of the groove forming pin 23 is flush with the core die surface. Next, resin is injected into the cavity 11 from the side gate 12 to fill the cavity 11, and the inner body 41 in which the display body 42 is partially projected on the upper surface is primarily molded.

When the movable die 2 is opened after molding such an inner body 41, the inner body 41 remains attached to the core die 21 and remains in the movable die 2 as shown in FIG. The gate holes 44, 44 formed by the pair of protrusions 13, 13 protruding toward the inside are formed in the surrounding portion 43 of the display body 42 and in the facing portion outside the display body 42a forming the surrounding portion 43. .

After the mold is opened, the movable mold 2 is moved together with the inner body 41 to the second fixed mold 3 to close the mold.
The inner body 41 is enclosed in the second fixed mold 3 to form a mold surface on one side of the cavity 31 up to a point where the mold body 2 contacts the mold surface. Therefore, the connection groove forming pin 23 is retracted by the projecting plate 25 and retracted into the rotary rod 22 to form the resin connection groove 5 extending between the lower surface of the inner body 41 and the tip surface of the pair of gate holes 44, 44. After that, a different color resin is injected and filled into the cavity 31 from the side gate 32.

The resin is the cavity 31 outside the display body 42.
The gate hole 44, the connection groove 5, and the gate hole 4
4 so that the main body 45 flush with the display body is filled into the surrounding portion 43 from 4 to form the two-color molded product 4 integrally secondary-molded on the upper surface of the inner body 41 up to the inside of the surrounding portion. Become.
When the rotary rod 22 is rotated by 90 ° by the rack 28 after the secondary molding of the main body 45, as shown in FIG. 8, the resin bridge 51 on the back surface of the molded product formed in the connection groove 5 also rotates together with the rotary rod 22. Gate cutting is performed, and the resin bridge 51 is separated from the back surface of the molded product.

When the movable mold 2 and the second fixed mold 3 are opened after this gate cutting, the two-color molded product 4 is omitted although not shown in the drawing.
Remains attached to the core mold 21 and is drawn out from the cavity 31 and remains in the movable mold 2. Therefore, the two-color molded product 4 is released from the mold by another normal projecting means (not shown). As shown in FIG. 9, the resin bridge 51 separated from the molded product remains in the tip of the rotating rod 22 as it is, but then the connecting groove molding pin 23 is moved forward by the projecting plate 25 to move the original core tip surface. When it is returned to the position, the resin bridge 51 is thereby projected and removed from the inside of the tip of the rotating rod.

The gate cutting by the rotation of the resin bridge 51 can be performed in parallel with the pressure-holding or cooling process, and optionally the mold-opening process of the second fixed mold 3, but before the resin is solidified. Most preferred. The resin forming the inner body 41 integral with the display body 42 and the resin forming the body 45 are different in color. However, when the inner body side is a transparent resin and the body side is an opaque resin, A secondary molded product having a display body capable of illuminated display in the main body surface can be molded by a molding means similar to the above. Further, since the mold device does not require an undercut for fixing the resin bridge, the structure inside the core mold is simplified, and the gate cut of the resin bridge is always performed reliably.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a mold device used in a two-color molding method according to the present invention.

FIG. 2 is a plan view of a movable type.

FIG. 3 is a vertical side view of the mold device.

FIG. 4 is a vertical sectional front view and a vertical sectional side view showing a molded state of the inner body.

FIG. 5 is a vertical sectional front view and a vertical sectional side view showing a releasing state of an inner body.

FIG. 6 is a vertical sectional front view and a vertical sectional side view showing a mold closed state of a movable mold and a second fixed mold.

FIG. 7 is a front view in vertical section at the time of molding the main body.

FIG. 8 is a vertical cross-sectional front view showing a gate cut state of a resin bridge.

FIG. 9 is a vertical sectional front view showing a mold release state of a two-color molded product.

[Explanation of symbols]

1 First fixed type 2 movable 3 second fixed type 4 two-color molded products 5 resin bridge 11 cavities 12 Display surface 13 Projection for gate hole formation 21 core type 22 rotating rod 23 Connection groove forming pin 23a Plate-shaped tip 25 protruding plate 26 gears 28 racks 31 cavity 41 inner body 42 Display 43 Surrounding part 44 gate hole 45 body 51 resin bridge

Claims (3)

[Claims] 1. An inner body in which a display body such as letters and numbers having a surrounding portion is partially projected on an upper surface, and a pair of gate holes are formed at inner and outer positions of the display body forming the surrounding portion. Resin is primary molded by injection of resin, and the connection grooves for both gate holes are formed on the lower surface of the inner body, and then a resin of a different color is injected flush with the display body on the upper surface of the inner body to form the main body inside the enclosure. A two-color molding method, characterized in that the gate of the resin bridge on the back surface of the molded product formed with the main body of the subsequent molding is cut by rotating the resin bridge before releasing the molded product. 2. An inner body in which a display body such as letters and numbers having a surrounding portion is partially projected on the upper surface, and a pair of gate holes are formed at the inner and outer positions of the display body forming the surrounding portion. To
After primary molding by injection of transparent resin that can display illumination, after forming the connection groove of both gate holes on the lower surface of the inner body,
The opaque resin is injected flush with the display on the upper surface of the inner body, and the main body is secondarily molded to the inside of the surrounding part, and the gate cut of the resin bridge on the back of the molded product that occurs with the main body is removed before releasing the molded product. A two-color molding method characterized by performing rotation of a resin bridge. 3. A mold surface for molding a display body such as letters and numbers having a surrounding portion, and a pair of projections for gate holes at inner and outer positions of the molding surface of the display body forming the surrounding portion. A first fixed mold having a cavity for molding the inner body, and a second fixed mold having a cavity for molding the main body on the upper surface of the inner body excluding the display body, with the inner body as the mold surface of the cavity,
A movable mold having a core mold for molding the lower surface of the inner body by closing the mold with the first fixed mold and a second fixed mold together with the inner body for molding the main body on the upper surface of the inner body, and the movable mold. A rotating rod and a rotating means, which are rotatably provided inside the mold and have their front end surfaces flush with the core mold surface, and a plate-like front end portion which is fitted into the center portion of the rotary rod to form the pair of protrusions. A two-color molding die device, comprising: a connecting groove forming pin facing the part so that it can come into contact with and separating from the part; and a protruding plate connecting the rear ends of the connecting groove forming pins protruding from the rotating rod.